The present invention is directed to luminescent materials, to methods of making such materials, and to methods of using such materials. More particularly, the present invention is directed to efficient narrow band ultra-violet (UV) emitting phosphors, especially useful for erythemal applications and as "black-lights".
Ultra-violet emitting phosphors are known in the art. See for example, U.S. Pat. Nos. 4,189,661 to Haugsjaa et al., 4,153,572 and 4,088,922 to Wolfe, 4,070,583 to Rabatin, 4,224,553 to Hellwig, and GB Pat. No. 1,565,811.
One such UV emitting phosphor is the GTE Sylvania Type 2011, which has the chemical formula BaSi.sub.2 O.sub.5 :Pb, and is available from the Chemical and Metallurgical Division, GTE Precision Materials Group, Towanda, PA 18848.
The present invention represents an alternative to the above-described phosphors having advantages over previous UV-emitting phosphors including; (1) a fluorescence in the UV spectral region at 330 nm, whose intensity under 254 nm, excitation exceeds that of the Ba silicate: Pb phosphor by as much as 18%. (2) a more favorable absorption than the Ba-silicate: Pb phosphor which permits it to also convert the 297 nm and 313 nm UV lines emitted by the Hg plasma into 330 nm emission. (3) An intense UV emission peaking at the wavelength location which should permit efficient sensitization of visible and near impared emissions from trivalent rare-earth cons, such as Tb.sup.3+, Dy.sup.3+, Tm.sup.3+ and Eu.sup.3+, and also for sensitization of the technologically important emission from Mn.sup.2+.